The bursting pulsar GRO J1744-28 is a Galactic low-mass X-ray binary that distinguishes itself by displaying type-II X-ray bursts: brief, bright flashes of X-ray emission that likely arise from spasmodic accretion. Combined with its coherent 2.1 Hz X-ray pulsations and relatively high estimated magnetic field, it is a particularly interesting source to study the physics of accretion flows around neutron stars. Here we report on Chandra/HETG observations obtained near the peak of its bright 2014 accretion outburst. Spectral analysis suggests the presence of a broad iron emission line centered at E_l ~ 6.7 keV. Fits with a disk reflection model yield an inclination angle of i ~ 52 degrees and an inner disk radius of R_in ~ 85 GM/c^2, which is much further out than typically found for neutron star low-mass X-ray binaries. Assuming that the disk is truncated at the magnetospheric radius of the neutron star, we estimate a magnetic field strength of B ~ (2-6)E10 G. Furthermore, we identify an absorption feature near ~6.85 keV could correspond to blue-shifted Fe xxv and point to a fast disk wind with an outflow velocity of v_out ~ (7.5-8.2)E3 km/s (~0.025c-0.027c). If the covering fraction and filling factor are large, this wind could be energetically important and perhaps account for the fact that the companion star lost significant mass while the magnetic field of the neutron star remained strong.
GRO J1744-28 (the Bursting Pulsar) is a neutron star LMXB which shows highly structured X-ray variability near the end of its X-ray outbursts. In this letter we show that this variability is analogous to that seen in Transitional Millisecond Pulsars such as PSR J1023+0038: 'missing link' systems consisting of a pulsar nearing the end of its recycling phase. As such, we show that the Bursting Pulsar may also be associated with this class of objects. We discuss the implications of this scenario; in particular, we discuss the fact that the Bursting Pulsar has a significantly higher spin period an…
GRO J1744-28, commonly known as the `Bursting Pulsar', is a low mass X-ray binary containing a neutron star and an evolved giant star. This system, together with the Rapid Burster (MXB 1730-33), are the only two systems that display the so-called Type II X-ray bursts. These type of bursts, which last for 10s of seconds, are thought to be caused by viscous instabilities in the disk; however the Type II bursts seen in GRO J1744-28 are qualitatively very different from those seen in the archetypal Type II bursting source the Rapid Burster. To understand these differences and to create a framework…
We analyzed RXTE/PCA observations of the bursting pulsar GRO J1744-28 during its two outbursts in 1995-1997. We have found a significant transition, i.e., a sharp change, of both spectral and timing properties around a flux of $\rm 10^{-8}\ ergs\ cm^{-2}\ s^{-1}$ (3-30 keV), which corresponds to a luminosity of 2--8$\rm \times 10^{37}\ ergs\ s^{-1}$ for a distance of 4--8 kpc. We define the faint (bright) state when the flux is smaller (larger) than this threshold. In the faint state, the spectral hardness increases significantly with the increasing flux, while remaining almost constant in the…
脉冲星零化是脉冲发射突然停止若干周期的现象。零化分数常被用来表征这种现象。提出了一种分析脉冲星零陷现象的新方法，该方法引入了两个关键参数：零陷度$χ$和零陷尺度$ N $，零陷度定义为零陷周期和爆发周期在直角坐标系中的夹角，零陷尺度定义为连续零陷周期和爆发周期的有效长度.调零程度$χ$可以通过$\tan χ= N_{\rm nulling} / N_{\rm bursting} $计算，并且平均值与调零分数相关，而调零尺度$ N $也是新定义的基本参数，其指示调零发生的频率。本文利用文献资料测定了10个标本的$χ$和$ N $的分布。我们发现零化度$χ$表示零化与爆发的相对长度，零化尺度$ N $与旋转频率的导数有关，从而与恒星旋转能量的损失率有关。它们的偏差反映了调零过程的随机性。
The X-ray pulsar GRO J1744-28 is a unique source which shows both pulsations and type-II X-ray bursts, allowing studies of the interaction of the accretion disk with the magnetosphere at huge mass accretion rates exceeding $10^{19}$ g s$^{-1}$ during its super-Eddington outbursts. The magnetic field strength in the source, $B\approx 5\times 10^{11}$ G, is known from the cyclotron absorption feature discovered in the energy spectrum around 4.5 keV. Here, we explore the flux variability of the source in context of interaction of its magnetosphere with the radiation-pressure dominated accretion d…
NICER detection of a new candidate cyclotron line in the bursting X-ray pulsar GRO J1744-28
College of Physics, Hebei Normal University（河北师范大学物理学院）；Institut für Astronomie und Astrophysik, Universität Tübingen（蒂宾根大学天文与天体物理研究所）；School of Physics, Nankai University（南开大学物理学院）；School of Physics and Astronomy, Sun Yat-Sen University（中山大学物理学院）；KeyLaboratory of Time and Frequency Primary Standards, Chinese Academy of Sciences（中国科学院时间频率基准重点实验室）；Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所粒子天体物理重点实验室）
The Neutron Star Interior Composition Explorer (NICER) has extensively monitored the August 2019 outburst of the 401 Hz millisecond X-ray pulsar SAX J1808.4-3658. In this Letter, we report on the detection of a bright helium-fueled Type I X-ray burst. With a bolometric peak flux of $(2.3\pm0.1)\times 10^{-7}$ erg/cm^2/s, this was the brightest X-ray burst among all bursting sources observed with NICER to date. The burst shows a remarkable two-stage evolution in flux, emission lines at $1.0$ keV and $6.7$ keV, and burst oscillations at the known pulsar spin frequency, with $\approx4$\% fraction…
Strong bursts from the anomalous X-ray pulsar 1E 1547.0-5408 observed with the INTEGRAL/SPI Anti-Coincidence Shield
2009年1月，不同的卫星从异常X射线脉冲星1 E 1547.0-5408的方向探测到多次短时间的软伽马射线爆发。在这里，我们报告的观测结果与INTEGRAL SPI-ACS探测器在最强的爆发活动期间。1月22日，在几个小时内探测到200多个能量超过80 keV的爆发。其中，两个非常明亮的事件显示出持续数秒的脉动尾部，并在1 E 1547.0-5408的2.1秒自旋周期进行调制。在这些爆发中，最亮的爆发释放的能量只有几个10^43尔格，假设距离为10千秒差距。这比从软伽马射线中继站观测到的三个巨型耀斑要小，但比从软伽马射线中继站和异常X射线中继站观测到的典型爆发要高。
Burst and Persistent Emission Properties during the Recent Active Episode of the Anomalous X-ray Pulsar 1E 1841-045
Swift/BAT于2010年5月检测到来自1 E 1841-045的第一次爆发，并记录了至少到2011年7月的间歇性爆发活动。在这里，我们提出了斯威夫特和费米/GBM观测这种爆发活动，并寻找相关的变化，持续的X射线发射源。爆发的T90持续时间在18-140 ms之间，与其他磁星爆发持续时间相当，而每个爆发释放的能量在（0.8 - 25）E38 erg之间，这是SGR爆发的低端。我们发现爆发活动对源的持续通量水平没有显著影响。我们认为，在1 E 1841-045导致这种零星的爆发活动的机制可能不涉及大规模的重组（无论是地壳或磁层）在其他磁星源。
We report on the 2020 reactivation of the energetic high-magnetic field pulsar PSR J1846-0258 and its pulsar wind nebula (PWN) after 14 years of quiescence with new Chandra and Green Bank Telescope observations. The emission of short-duration bursts from J1846-0258 was accompanied by an enhancement of X-ray persistent flux and significant spectral softening, similar to those observed during its first bursting episode in 2006. The 2020 pulsar spectrum is described by a powerlaw model with a photon index Gamma=1.7\pm0.3 in comparison to a Gamma=1.2\pm0.1 before outburst and shows evidence of an …
Recently, repeating fast radio bursts (FRBs) with a period of $P_{\rm FRB}=16.35\pm0.18$ days from FRB 180916.J0158+65 had been reported. It still remains controversial how to give rise to such a periodicity of this FRB. In this Letter, based on an assumption of a young pulsar surrounding by a debris disk, we attempt to diagnose whether the Lense-Thirring precession of the disk on the emitter can produce the observed periodicity. Our calculations indicate that the Lense-Thirring effect of a tilted disk can result in a precession period of 16 days for a mass inflow rate of $0.5-1.5\times10^{18}…
We report the discovery of absorption features in the X-ray spectrum of the transient X-ray pulsar GROJ2058+42. The features are detected around $\sim10$, $\sim20$ and $\sim30$ keV in both NuSTAR observations carried out during the source type II outburst in spring 2019. The most intriguing property is that the deficit of photons around these energies is registered only in the narrow phase interval covering around 10% of the pulsar spin period. We interpret these absorption lines as a cyclotron resonant scattering line (fundamental) and two higher harmonics. The measured energy allow us to est…
Long-term spectral and timing properties of the soft gamma-ray repeater SGR 1833-0832 and detection of extended X-ray emission around the radio pulsar PSR B1830-08
We report results of the first broadband observation of the transient X-ray pulsar GRO J1008-57 performed in the quiescent state. Observations were conducted quasi-simultaneously with the Mikhail Pavlinsky ART-XC telescope on board SRG and NuSTAR right before the beginning of a Type I outburst. GRO J1008-57 was detected in the state with the lowest observed luminosity around several $\times 10^{34}$ erg s$^{-1}$ and consequently accreting from the cold disk. Timing analysis allowed to significantly detect pulsations during this state for the first time. The observed pulsed fraction of about 20…
The first known pulsar glitch was discovered in the Vela pulsar at both Parkes and Goldstone in March 1969. Since then the number of known glitches has grown enormously, with more than 520 glitches now known in more than 180 pulsars. Details of glitch parameters and post-glitch recoveries are described and some implications for the physics of neutron stars are discussed.
The results of the broadband spectral and timing study of the transient X-ray pulsar GRO J2058+42 in a wide energy range at a low luminosity $L_{x} \simeq 2.5\times 10^{36}$ erg s$^{-1}$ are reported. The data revealed that the pulse profile and pulse fraction of the source are significantly changed in comparison with previous NuSTAR observations, when the source was ten times brighter. The cyclotron absorption line at $\sim10$ keV in the narrow phase interval is consistent with the high state observations. Spectral analysis showed that at high luminosities $L_{x}\simeq (2.7-3.2)\times 10^{37}…
The low braking-index pulsar PSR J1734$-$3333 could be born with superhigh internal magnetic fields $B_{\rm in}\sim10^{15}-10^{16}$ G, and undergo a supercritical accretion soon after its formation in a supernova explosion. The buried multipole magnetic fields will merger into a dipole magnetic field. Since the magnetic flow transfers from the core to the crust of the pulsar, its surface dipole field grows quickly at a power-law form assumed until it saturates at the level of internal dipole field. The increase in surface dipole magnetic field results in the observed low braking index of $n=0.…
Recent observations of repeating fast radio bursts (FRBs) suggest that some FRBs reside in an environment consistent with that of binary neutron star (BNS) mergers. The bursting rate for repeaters could be very high and the emission site is likely from a magnetosphere. We discuss a hypothesis of producing abundant repeating FRBs in BNS systems. Decades to centuries before a BNS system coalesces, the magnetospheres of the two neutron stars start to interact relentlessly. Abrupt magnetic reconnection accelerates particles, which emit coherent radio waves in bunches via curvature radiation. FRBs …
A Burst in a Wind Bubble and the Impact on Baryonic Ejecta: High-Energy Gamma-Ray Flashes and Afterglows from Fast Radio Bursts and Pulsar-Driven Supernova Remnants
Pulsars play a crucial astrophysical role as the highly energetic compact radio, X-ray, and gamma-ray sources. Our previous works show that the radio pulsars found as the pulsing gamma sources by the Large Area Telescope (LAT) on the board of the Fermi Gamma-Ray Space Telescope have high values of magnetic field near the light cylinder, two-three orders of magnitude stronger comparing with the magnetic fields of radio pulsars: $\log B_{lc}$ (G) are 3.60-3.95 and 1.75. Moreover, their losses of the rotation energy are also three orders higher than the corresponding values for the main group of …
Time-dependent cascades of electron-positron pairs are thought to be the main source of plasma in pulsar magnetospheres and a primary ingredient to explain the nature of pulsar radio emission, a longstanding open problem in high-energy astrophysics. During these cascades - positive feedback loops of gamma-ray photon emission, via curvature radiation by TeV electrons and positrons, and pair production -, the plasma self-consistently develops inductive waves that couple to electromagnetic modes capable of escaping the pulsar dense plasma. In this work, we present an analytical description of pai…
The Be X-ray binary GRO J2058+42 recently went through a Type-II outburst during March-April 2019 lasting for about 50 days. This outburst was detected with the operating all sky X-ray monitors like the Fermi-GBM, Swift-BAT and MAXI-GSC. Two NuSTAR observations were also made, one during the rise and other during the decay of the outburst. It gave us the unique opportunity to analyze the broadband characteristics of the pulsar for the first time and accretion torque characteristics of the pulsar over a range of X-ray luminosity. The pulse profiles are strongly energy dependent, with at least f…
继1991年Wolszczan发现脉冲星PSR B 1257 +12周围的行星之后，目前已发现了200多个行星系中的300多颗行星，因此Wolszczan的发现意义不可低估。在本文中，我们的目标是说服读者，伴随脉冲星PSR B1257+12的物体比迄今为止想象的更奇特。它们可能不是普通的行星，而是矮奇异夸克星，而脉冲星可能是标准质量的夸克星，而不是中子星。如果是这样的话，这将表明奇异夸克物质是物质的基态。
